Method for rapidly mixing fluids

ABSTRACT

A method for rapidly mixing at least one fluid into another by disposing a first fluid within a first conduit and flowing a second fluid within a second conduit substantially concentric with and disposed within the first conduit, the second conduit opening into contact with the fluid within the first conduit. An angular momentum is imparted to the second fluid within the second conduit to thereby form a swirling jet of the second fluid as it exits from the second conduit into contact with the fluid disposed in the first conduit.

United States Patent Inventor Vitold 1R. Kruka Houston. Tex.

Appl. No. 1.160

Filed Jan. 7, 1970 Patented Nov. 16, 1971 Assignee Shell Oil Company NewYork, N.Y.

METHOD FOR RAPIDLY MIXING FLUIDS 3 Claims, 4 Drawing Figs.

U.S. Cl 259/25 Int. Cl 801i 7/02 Field oi'Search 259/l8.4. 9. IO, 25,26. 36, 45. 46

References Cited UNITED STATES PATENTS 12/1950 Fash 1831.754 4/1958Manka 4. 259/4 X 3 l47 7l7 9/l964 Smith, 259/4 X 3.286.992 ll/l966Armeniades 4 4 i 259/4 Primary Examiner-Robert W Jenkins Armrneys-LouisJ. Bovasso and J H McCarthy ABSTRACT: A method for rapidly mixing atleast one fluid into another by disposing a first fluid within a firstconduit and flowing a second fluid within a second conduit substantiallyconcentric with and disposed within the first conduit, the secondconduit opening into contact with the fluid within the first conduit. Anangular momentum is imparted to the second fluid within the secondconduit to thereby form a swirling jet of the second fluid as it exitsfrom the second conduit into contact with the fluid disposed in thefirst conduit PATENTEnunv 16 I97! 8.620, 507' sum 1 or 2 INVENTOR:

VITOLD R. KRUKA oZ M HIS ATTORNEY PATENTEDuuv 16 I971 3, 620.507

sum 2 OF 2 INVENTOR:

VITOLD R. KRUKA BWJW HIS ATTORNEY BACKGROUND OF THE INVENTION 1. Fieldof the Invention This invention relates to the mixing of fluids; and,more particularly, to a method for rapidly mixing one fluid intoanother.

2. Description of the Prior Art Rapid mixing of fluids is necessarywhenever it is undesirable to have the two or more fluids, which are tobe mixed, in contact with each other in an unmixed state over extendedperiods of time. For example, a paraxylene unit was found to producecrystals too small in size which led to the waste discharge ofapproximately percent of the production. Indications were that thiscondition was due to an overproduction of crystal nueleii which in turnis strongly dependent on the level of local supersaturation.

In this paraxylene unit, a stream rich in paraxylene is fed into areactor whose fluid phase has a low paraxylene content and a lowertemperature than the feed. If the feed maintains itself in lumps overextended periods of time, then local supersaturation occurs as moleculartransfer of heat is higher than that of mass. Thus, the longevity of theunmixed feed lumps determines the number of nucleation sites and finalcrystal size. To increase the crystal size, the average lifetime of theunmixed fluid lumps must be decreased.

Certain prior art patents are directed to the mixing of fluids. Thesepatents, however, fail to achieve rapid mixing rates. For example, inUS. Pat. No. 3,286,992, two fluids are mixed in a tube and are incontact with curved elements therein which split the incoming fluids,already in contact with each other, into two streams. Eddying motion isimparted to each stream to promote mixing. However, such action is notrapid as the two fluids coexist in the tube as unmixed lumps for asubstantial amount of time. The same comments apply to the methoddisclosed in US. Pat. No. 3,424,347 where two viscous fluids areinjected into a plurality of finned tubes under laminar flow conditions.Mixing, implied to occur inside the tubes, is achieved by subdivisionand interlacing of the fluid streamlines.

SUMMARY OF THE INVENTION It is an object of this invention to provide animproved method of rapidly mixing one fluid into another.

It is a further object of this invention to provide a method of rapidlymixing one fluid into another whereby the rate of mixing may becontrolled.

These and other objects are preferably accomplished by disposing a firstfluid within a first conduit and flowing a second fluid within a secondconduit substantially concentric with and disposed within the firstconduit, the second conduit opening into contact with the fluid withinthe first conduit. An angular momentum is imparted to the second fluidwithin the second conduit to thereby form a swirling jet of the secondfluid as it exits from the second conduit into contact with the fluiddisposed in the first conduit.

The fluid to be mixed is injected into the other which may be at rest,as in a batch-type reactor, or which may be flowing at a lower velocitythan the first fluid. The angular momentum may be imparted to the fluideither by internal or external means.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric view of apreferred embodiment of apparatus for carrying out the method of myinvention;

FIG. 2 is an isometric view, partly in section, of a portion of theapparatus of FIG. 1;

FIG. 3 is an isometric view of an alternate embodiment of apparatus forcarrying out the method of my invention; and

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, FIG.1 shows an outer conduit I0 having a first fluid flowing therethrough inthe direction of arrows 11. A second conduit 12, substantiallyconcentric with conduit 10, is disposed internally thereof. A secondfluid is adapted to be flowed in conduit 12 as indicated by the arrowI4. Although both fluids are shown in FIG. I as flowing through conduits10 and 12, the fluid in conduit 10 may be either at rest or flowing at alower velocity than the jet of fluid from conduit 12 as will bediscussed further hereinbelow.

A swirl or angular momentum is imparted to the fluid exiting fromconduit 12. The phrase angular momentum refers to a change in the normalspread of the fluid exiting from conduit 12. For example, as illustratedin FIG. 2, a helix 15 having a plurality of helical fins 15a, ispreferably fixedly mounted in conduit 12. In this manner, low values ofswirl may be imparted to the fluid exiting from conduit 12 thus fonninga swirling jet 16 (FIG. 1) of fluid. The dotted lines in FIG. I indicatethe spread of the fluid which would be fonned by not swirling the fluid.Thus, it can be seen that the helical fins 15a disperse or mix the fluidfrom conduit I2 into the fluid in conduit 10 more rapidly in both spaceand time. The ratio of angular to linear jet momentum may be controlledby varying the pitch of helix 15.

Thus, the rate of mixing of a swirling jet above that of a nonswirlingjet may be controlled by the amount of angular momentum given to thejet. For higher values of swirl, the angular momentum may be impartedthrough external means. For example, as illustrated in FIG. 3, a furtherembodiment of the invention is shown wherein a first fluid is flowed ina conduit 16 in the direction of the arrow 17 while a second fluid isflowed in a conduit 18 in the direction of the arrow I9. Again, thefluid flowing in conduit 16 may be either at rest or flowing asdiscussed hereinabove. The external means for imparting angular momentumto the fluid in conduit 18 may take the form of a plurality of radiallyextending fins 20 having fingers 20a at their extremities (FIG. 4),mechanically or automatically rotated by a connecting shaft 21 (FIG. 3)preferably extending longitudinally of conduit 18 and coupled toactuating means (not shown), such as a motor or a handle. Note that fins20 are substantially linearly extending and substantially perpendicularto the direction of the flowing fluid in conduit 18. In this manner, aswirling jet 22 is formed by the fluid exiting from conduit 18.

As set forth hereinabove, rapid mixing of one fluid into another may beachieved by forming a swirling jet at the point of contact of a firstfluid with a second fluid. The mixing action is due to the dispersivequalities of the angular momentum imparted to the first fluid and theturbulence inherent in jets of sufficiently high Reynolds numbers. Thefluid to be mixed is injected into the other fluid which may be at rest,as in a batch-type reactor, or which may be flowing, but at a lowervelocity than the jet. This angular momentum may be imparted by eitherinternal means, such as the fixed, helical fins 15a of the helix 15 ofFIG. 2 or by external means, such as the radially and linearly extendingrotating fins 20 of FIG. 4. The rate of mixing of the first fluid intothe second fluid may be controlled by controlling the angular and linearmomentum of the issuing fluid.

In one preferred use of the method of this invention, a stream rich inparaxylene may be fed into a reactor whose fluid phase has a lowparaxylene content and preferably a lower temperature than the feedusing either of the embodiments of the invention described hereinabove.In this manner, the feed is rapidly dispersed into the reactor contentsfrom the combined angular momentum of the feed after it leaves thenozzle (i.e., the outlet of the second conduit) and the turbulenceinherent in jet flows.

I claim as my invention:

1. A method for rapidly mixing at least one fluid into anothercomprising the steps of:

disposing a first fluid at rest within a first conduit;

flowing a second fluid within a second conduit substantially concentricwith and disposed within said first conduit, said second conduit openinginto the fluid within said first conduit; and

imparting an angular momentum only to said second fluid within saidsecond conduit to thereby form a swirling jet of said second fluid as itexits from said second conduit into contact with the fluid disposed insaid first conduit.

2. A method for rapidly mixing at least one fluid into anothercomprising the steps of:

disposing a first fluid within a first conduit;

flowing a second fluid within a second conduit substantially concentricwith and disposed within said first conduit, said second conduit openinginto the fluid within said first conduit; and

imparting an angular momentum to said second fiuid within said secondconduit by rotating a plurality of radially extending fins in the pathof said fluid flowing in said second conduit, said fins beingsubstantially linearly extending and substantially perpendicular to thedirection of the flowing fluid in said second conduit to thereby form aswirling jet of said second fluid as it exists from said second conduitinto contactwith the fluid disposed in said first conduit.

3. A method for rapidly mixing at least one fluid into anothercomprising the steps of:

flowing a first fluid within a first conduit;

flowing a second fluid faster than said first fluid within a secondconduit substantially concentric with and disposed within said firstconduit, said second conduit opening into the fluid within said firstconduit; and

imparting an angular momentum only to said second fluid within saidsecond conduit to thereby form a swirling jet of said second fluid as itexits from said second conduit into contact with the fluid disposed insaid first conduit.

'0' I I l t

1. A method for rapidly mixing at least one fluid into anothercomprising the steps of: disposing a first fluid at rest within a firstconduit; flowing a second fluid within a second conduit substantiallyconcentric with and disposed within said first conduit, said secondconduit opening into the fluid within said first conduit; and impartingan angular momentum only to said second fluid within said second conduitto thereby form a swirling jet of said second fluid as it exits fromsaid second conduit into contact with the fluid disposed in said firstconduit.
 2. A method for rapidly mixing at least one fluid into anothercomprising the steps of: disposing a first fluid within a first conduit;flowing a second fluid within a second conduit substantially concentricwith and disposed within said first conduit, said second conduit openinginto the fluid within said first conduit; and imparting an angularmomentum to said second fluid within said second conduit by rotating aplurality of radially extending fins in the path of said fluid flowingin said second conduit, said fins being substantially linearly extendingand substantially perpendicular to the direction of the flowing fluid insaid second conduit to thereby form a swirling jet of said second fluidas it exists from said second conduit into contact with the fluiddisposed in said first conduit.
 3. A method for rapidly mixing at leastone fluid into another comprising the steps of: flowing a first fluidwithin a first conduit; flowing a second fluid faster than said firstfluid within a second conduit substantially concentric with and disposedwithin said first conduit, said second conduit opening into the fluidwithin said first conduit; and imparting an angular momentum only tosaid second fluid within said second conduit to thereby form a swirlingjet of said second fluid as it exits from said second conduit intocontact with the fluid disposed in said first conduit.